The Effect of Mild Dehydration Induced by Heat and Exercise on Cognitive Function

Abstract

Background: Past studies have demonstrated cognitive impairment after dehydration, though results are not always consistent. Methodological differences may account for these discrepan- cies. Therefore, the purpose of the present study was to determine the effects of mild dehydra- tion on various domains of cognitive function. Methods: Twenty-seven men (n=14; 26.9±4.6 years; 176.3±6.6 cm; 79.1±9.0 kg) and women (n=13; 27.3±4.3 years; 171.0±6.5 cm; 66.5±4.5 kg) participated in the study. Subjects were dehydrated to approximately 2% body mass loss via treadmill running and sauna. Measure- ments were collected prior to and after dehydration. Cognitive function tests included: Finger tapping, symbol digit coding, Stroop, and shifting attention tests. Results: Reaction time during the shifting attention test was significantly lower from pre-test- ing to post-testing (PRE: 882.67±126.59 ms; POST: 830.00±105.83 ms; p=0.0012). The Stroop reaction time was significantly lower from pre-testing to post-testing (PRE: 712.56±97.52 ms; POST: 671.63±97.21 ms; p=0.02). No significant changes were observed in any other measure- ments. Conclusion: Dehydration may enhance cognitive functioning in the areas of Stroop reaction time and reaction time during the shifting attention test.